<!DOCTYPE html>
<html lang="zh_CN">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        p{
            color: red;
        }

        #p1{
            font-size: 20px;
        }

        .p1{
            border: 1px solid #000;
        }

        .warn{
            background-color: #ccc;
        }

        .fz{
            font-size: 20px;
        }
        /*通配符选择，代表页面上所有的元素*/
        *{

        }
    </style>
</head>
<body>
    <p id="p1" class="p1 warn">段落1</p>
    <p id="p2" class="warn p1 fz">段落2</p>
</body>
<script type="text/javascript">

</script>

</html>
